Tech idiocy - laptop batteries

I feel like a complete technological ignoramus posting this but it's the first time I've had the problem:

The battery of my laptop, purchased around 2 1/2 years ago, has suddenly become very unreliable when the machine is not plugged in. What I thought would be a simple procedure, i.e. replacing the battery, seems much more complicated with a glut of info online on 'fake' replacements, an £80 price tag on the battery, and no clear info as to which models accept which battery.

Simple question - is there any downside aside from electricity costs to just plugging the machine in as and when I need it? As I understand it, this isn't a problem for lithium-ion batteries, but I wanted to doublecheck with any tech-savvy people here.

The Following User Says Thank You to droid For This Useful Post:

I just got a new MacBook Pro after just finishing using a four-year old one, and always have them plugged in when working. doesn't seem to affect the cycle of the battery when I'm out and not plugged in.